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Why too much calcium causes muscle weakness?





likeabreeze
As far as I know, calcium is essential for the muscle contraction.
At the neuromuscular junction, the Ca2+ comes into the prejunctional membrane to extract acetylcholine to activate the muscle.
And the Troponin C in the muscle cell has to bond with Ca2+.
you see, without Ca2+, the muscle can't function well.
But, why, too much calcium causes muscle weakness?
Ankhanu
Molecular bio isn't really my thing, but, a quick skim around suggests that high calcium concentration alters the permeability of nerve cell membranes to sodium, reducing permeability. Reduced permeability reduces the action potential of the cells, causing them to fire less consistently, resulting in less reactive muscle cells, since they're not getting the message to contract.

This was from a pretty quick google scholar search, from someone who's last molecular biology course was back in 2003... so, take it with a grain of salt, and look into it more closely Wink
likeabreeze
Ankhanu wrote:

This was from a pretty quick google scholar search, from someone who's last molecular biology course was back in 2003... so, take it with a grain of salt, and look into it more closely Wink

Thanks.
what is the url? I am eager to know about that.
high calcium concentration alters the permeability of nerve cell membranes to sodium.
this seems reasonable, because Na+ has to come into the nerve cell to produce an action potential.
Ankhanu
I believe I used a search term along the lines of ' mechanism weakness Hypercalcemia ', perused a couple of the hits that appeared reputable, most of them making reference to sodium permeability and action potentials, then hit google scholar, with a term like ' Hypercalcemia sodium permeability ' to quickly check some primary literature on the topic to make sure the popular sites had some basis.

I really didn't spend much time checking, so you'd be well advised to check on my result; maybe hit pubmed too.
mshafiq
Excess of every thing is bad. Always eat in balance.Balance diet is good for health.Always try to drink low fat milk.And also doctor suggest that kids should drink low fat 2% milk.
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